Pest insects adversely affect agriculture production by decreasing crop yield and/or crop quality. One way to control pest insects involves disrupting metabolic functions that are vital to insect development and growth.
The ecdysteroids ecdysone (“ECD”) and 20-hydroxyecdysone (“20E”) play an important role in insect development. Ecdysteroid pulses regulate larval molts, larval and prepupal transitions, and differentiation of adult tissues during pupation. See e.g., Riddiford, L. M. (1993), Hormones and Drosophila Development, In The Development of Drosophila melanogaster, Vol. II (ed. M. Bate and A. Martinez Arias), pp. 899–939, Cold Spring Harbor, Cold Spring Harbor Press. Ecdysteroids also regulate oogenesis and patterning of the embryonic cuticle. See e.g., Buszczak et al. (1999) Development 126:4581–4589; Bender et al. (1997) Cell 91:777–788; Henrich et al. (1999) Peptide hormones, syteroid hormones and puffs: Mechanisms and models in insect development, In Vitamins and Hormones (ed. Litwack) Vol. 55, pp. 73–125, Academic Press, San Diego.
Insects cannot make the cyclopentanoperhydrophenanthrene structure of ecdysteroids de novo, and build ecdysteroids from dietary steroids (e.g., cholesterol and phytosteroids). Generally, biosynthesis of ECD and 20E from cholesterol involves a series of oxidation, reduction and hydroxylation steps. See e.g., Gilbert et al., Control and Biochemical Nature of the Ecdysteroidogenic Pathway, Ann Rev Entomology (in press). 20E is made from ECD.
While the ecdysteroid biosynthetic pathway and the effects of ECD and 20E on insect development are relatively well characterized, the identity of the genes and proteins involved in ecdysteroid biosynthesis is as yet largely unknown.